In a skillet, cook beef over medium heat, breaking into crumbles, until no longer pink, 5-7 minutes; drain. Add onion and garlic salt to beef; continue to cook until onion is soft. Stir in the flour; cook and stir 2-3 minutes. Add water or beef broth, condensed soup and mushrooms; bring to a simmer. Reduce heat; cook, stirring occasionally, 8-10 minutes. , Gently fold in sour cream; heat only until warm. Add salt and pepper to taste. Serve over noodles or rice and if desired, top with parsley.